This document discusses the concepts of total angular momentum, orbital angular momentum, spin angular momentum, and their quantum numbers. It explains how the angular momenta are combined vectorially to give the total angular momentum. Spin-orbit coupling arises from the interaction of an electron's spin and orbital angular momentum with an internal magnetic field. Hund's rules describe how the total electron configurations are determined in many-electron atoms. LS and jj coupling schemes are described for combining the angular momenta in atoms.